I turned to v3 and I've some problem with the web server.
when I browse into catégories (autors, séries ...) There is a new window with the letters A to Z. When I click a letter there is a error window like attached img so I can't browse by catégories.
At home of web browser there is also 2 biblio as I've got only one ...
Any help or suggestion ?

I'm running calibre on linux mint 18.1 x64 cinnamon.
(I tryed to copy the calibre folder to another place and rebuild the data base but it's the same)
Thanks
Beber

Thank you for your support
just install v3.1 last version, and the problem persist.
I search for a solution such it seams that I'm the only one having this problem.
The problem appears on my android smatphone, android tablet, and linux mint PC. I'm using for all devices Mozilla Firefox browser.
So I thaught it would be a Firefox issue. So I installed Chrome web browser, and the problem doesn't appear.
So my conclusion is : This problem seams to be a Firefox compatibility issue.
Regards,

Ok so, I refreshed in the browser but doesn't work.
So I go to advanced and delete manually the cach.
And I worked !!
So my problem is solved .. Computing is not so easy !
Thanks a lot for your support, and for Calibre, the best application in the world !
Regards,